A RAMO4 substrate is formed from single crystal represented by a formula of RAMO4 (in the formula, R indicates one or a plurality of trivalent elements selected from a group consisting of Sc, In, Y, and a lanthanoid element, A indicates one or a plurality of trivalent elements selected from a group consisting of Fe(III), Ga, and Al, and M indicates one or a plurality of bivalent elements selected from a group consisting of Mg, Mn, Fe(II), Co, Cu, Zn, and Cd). As one of such a RAMO4 substrate, a ScAlMgO4 substrate is known. A ScAlMgO4 substrate is used as a substrate for growing nitride semiconductor such as GaN (see Japanese Patent Unexamined Publication No. 2015-178448, for example). FIG. 1 illustrates an example of a manufacturing method of a conventional ScAlMgO4 substrate disclosed in Japanese Patent Unexamined Publication No. 2015-178448. As illustrated in FIG. 1, the conventional ScAlMgO4 substrate is manufactured by cleaving a ScAlMgO4 bulk material.